Processes for forming an aldehyde by the reaction of an olefin with carbon monoxide and hydrogen are known as hydroformylation processes or oxo processes. For many years, all commercial hydroformylation reactions employed cobalt carbonyl catalysts which required relatively high pressures (often on the order of 100 atmospheres of higher) to maintain catalyst stability. Such processes are described, for example, in British Patent Specification No. 1,120,277 which, inter alia, discloses the coreaction of ethylene and propylene. The data in this British Patent Specification indicates that the presence of ethylene negatively influences the production of butyraldehydes from the propylene in terms of the weight of aldehydes produced in a given time using a given quantity of catalyst.
U.S. Pat. No. 3,527,809 discloses a significantly improved hydroformylation process whereby alpha-olefins are hydroformylated with carbon monoxide and hydrogen to produce aldehydes in high yields at low temperature and pressures. The normal to iso-(or branched-chain) aldehyde isomer ratio of the product aldehydes is high. This process employs certain rhodium complex catalysts and operates under defined reaction conditions to accomplish the olefin hydroformylation. Since this process operates at significantly lower pressures than required theretofore in the prior art as typified by the aforementioned British Patent Specification, substantial advantages are realized including lower initial capital investment and lower operating costs. Further, the more desirable normal aldehyde isomer can be produced in high yields. The rhodium catalyzed process of U.S. Pat. No. 3,527,809 is at times referred to as the "low pressure oxo process" and is so referred to herein.
Several patents and patent applications disclose improvements in the low pressure oxo process. These includes U.S. Pat. No. 3,917,661, U.S. Pat. No. 4,148,830, U.S. Pat. No. 4,143,075, Belgium Pat. No. 856,542, Belgium Pat. No. 853,377, Belgium Pat. No. 863,267, Belgium Pat. No. 863,268, U.S. patent applications Ser. No. 051,189, filed June 22, 1979, U.S. patent application Ser. No. 079,884, filed Sept. 28, 1979, U.S. patent application Ser. No. 040,913 filed May 21, 1979, and U.S. patent application Ser. No. 090,140, filed Nov. 1, 1979. Other patents relating to the low pressure oxo process include Belgium Pat. No. 821,637.
However, none of the above-mentioned patents or applications relating to the low pressure oxo process specifically disclose the use of ethylene and a higher olefin in combination in that process or suggest that the use of such coreactants in that process would be free of the production limitations implied by the data in British Patent Specification No. 1,120,277.